Controlled release pharmaceutical formulations of nitazoxanide

ABSTRACT

Solid dosage formulations of nitazoxanide or a nitazoxanide analogue are provided that comprise a controlled release portion and an immediate release portion. The pharmaceutical composition is typically in the form of a bilayer solid oral dosage form comprising (a) a first layer comprising a first quantity of nitazoxanide or analogue thereof in a controlled release formulation; and (b) a second layer comprising a second quantity of nitazoxanide or analogue thereof in an immediate release formulation. Method of using the formulations in the treatment of hepatitis C are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.15/814,850, filed Nov. 16, 2017, which is a Continuation of U.S.application Ser. No. 15/141,921, filed Apr. 29, 2016, which is aContinuation of U.S. application Ser. No. 13/954,184, filed Jul. 30,2013, which is a Divisional of U.S. application Ser. No. 12/656,704,filed Feb. 12, 2010, which claims priority to U.S. ProvisionalApplication No. 61/202,285, filed Feb. 13, 2009, the entire contents ofwhich are incorporated herein by reference.

BACKGROUND

Nitazoxanide (2-(acetolyloxy)-N-(5-nitro-2-thiazolyl) benzamide) is acompound having the following structure:

The preparation and uses of this compound are disclosed, for example, inU.S. Pat. No. 3,950,351 to Rossignol.

Pharmaceutical compositions containing nitazoxanide and its metabolite,tizoxanide, were originally developed and marketed for treatingintestinal parasitic infections.

Following oral administration of nitazoxanide or mixtures ofnitazoxanide plus tizoxanide in humans, these compounds are partiallyabsorbed from the intestinal tract, and nitazoxanide is rapidlyhydrolyzed to form tizoxanide in plasma. Tizoxanide isglucurono-conjugated, and the drug is eliminated in urine and bile astizoxanide or tizoxanide glucuronide. The half-life of tizoxanide inplasma is only approximately 1.5 hours.

For treating intestinal infections, pharmaceutical compositionscontaining nitazoxanide or mixtures of nitazoxanide and tizoxanide and awetting agent and optionally a starch derivative have been usedsuccessfully. The use of particles of active ingredients ranging between5 and 200 μm was shown to be important to achieving safety and efficacy.The use of a pharmaceutically acceptable acid has been shown to improvethe stability of these pharmaceutical compositions. See, for example,U.S. Pat. Nos. 5,387,598; 5,968,961; and 6,117,894 to Rossignol. Tabletand suspension formulations have been shown to be equally effective fortreating intestinal parasitic infections regardless of their relativebioavailability.

The absorption of nitazoxanide and nitazoxanide-tizoxanide mixtures fromthe intestinal tract varies significantly depending on thepharmaceutical formulation. For example, the relative bioavailability ofan oral suspension has surprisingly been shown to be only 70% of that ofa tablet. Systemic bioavailability of these compounds has not been ofparamount importance, however, because the compounds have been usedalmost exclusively for treating parasites that reside in the lumen ofthe intestinal tract or in the intestinal mucosa.

Nitazoxanide and tizoxanide have also been shown to be active in vitroagainst certain DNA viruses in vitro (see, for example, U.S. Pat. Nos.5,578,621 and 5,886,013, to Rossignol). In recent years, they weresurprisingly shown to have activity against hepatitis C virus (HCV), anRNA virus, in vitro and in clinical trials (Reference pending USapplication, “Viral Hepatitis Treatment”). The mechanism of action ofnitazoxanide and tizoxanide in inhibiting virus replication is notknown, but it has been postulated to be a “cell-mediated” mechanismbecause of its broad spectrum antiviral activity and the inability toinduce resistance.

Early clinical trials of nitazoxanide and tizoxanide in treating chronichepatitis C were conducted using a tablet formulation developed fortreatment of intestinal parasitic infections. That tablet contained 500mg of active ingredient (99% nitazoxanide/1% tizoxanide). In patientschronically infected with HCV genotype 4, sustained virologic response(SVR) rates of 61% to 80% were achieved when the tablets wereadministered one tablet twice daily for 4 to 12 weeks followed by thesame regimen plus standard doses of peginterferon α-2a with or withoutribavirin for 36 weeks. By contrast, patients treated with the standardtherapy, peginterferon α-2a plus ribavirin for 48 weeks, experiencedonly a 50% SVR rate.

While early trials in patients with chronic hepatitis C genotype 4showed improved efficacy using the 500 mg tablet, a significant numberof patients were not cured. Higher doses of active ingredient could notbe used to improve efficacy because previous studies have shown thatdoses of 1000 mg twice daily are associated with a significant increasein side effects, which are primarily related to the intestinal tract(e.g., abdominal pain, diarrhea and nausea). These side effects reducepatient compliance with the treatment regimen and are particularlyunacceptable for long-term treatment of patients with hepatitis C.

For treating chronic HCV infection, tizoxanide must be delivered intothe bloodstream and to the infected hepatocytes. Ideally, the drugshould be administered by oral route no more often that twice daily andwithout significant side-effects in order to maximize the adherence ofpatients to the treatment regimen.

The variable absorption of nitazoxanide and tizoxanide in differentdosage formulations, the very short half-life of tizoxanide in plasmaand side-effects associated with high doses of nitazoxanide andtizoxanide in the intestinal tract are problems that must be overcome indeveloping a new optimized dosage formulation for treating chronichepatitis C. Furthermore, because the mechanism of action ofnitazoxanide against HCV is unknown, it is impossible to know whetherfluctuations in peak and trough concentrations at the site of infectionare beneficial or detrimental to improving efficacy.

Thus, there is a need for a solid dosage formulation of nitazoxanideand/or tizoxanide with improved efficacy in treating chronic hepatitis Ccompared to tablets described in the prior art, and without any increasein side effects.

SUMMARY

Controlled release formulations of nitazoxanide and nitazoxinideanalogues are described, as well as method of using the formulations inthe treatment of hepatitis C. In particular, solid dosage formulationsof nitazoxanide and nitazoxinide analogues are described that comprise acontrolled release portion and an immediate release portion.

Thus, in some aspects, a pharmaceutical composition in the form of asolid dosage form is provided, the composition comprising (a) a firstportion comprising a first quantity of nitazoxanide or an analoguethereof in a controlled release formulation; and (b) a second portioncomprising a second quantity of nitazoxanide or an analogue thereof inan immediate release formulation. In some embodiments, the compositionis a solid oral dosage form in the form of a tablet or, in otherembodiments, in the form of a capsule.

In other aspects, a method is provided for treating a patient sufferingfrom hepatitis C, the method comprising administering to the patient atherapeutically effective amount of a pharmaceutical composition in theform of a solid dosage form, the composition comprising (a) a firstportion comprising a first quantity of nitazoxanide or an analoguethereof in a controlled release formulation; and (b) a second portioncomprising a second quantity of nitazoxanide or an analogue thereof inan immediate release formulation.

In yet other aspects, a method is provided for treating a patientsuffering from hepatitis C, the method comprising (i) pretreating thepatient by administering to the patient for a period of time a firstcomposition in the form of a solid oral dosage form comprisingnitazoxanide or an analogue thereof as a first active agent, wherein thefirst composition comprises (a) a first portion comprising a firstquantity of nitazoxanide or analogue thereof in a controlled releaseformulation, and (b) a second portion comprising a second quantity ofnitazoxanide or analogue thereof in an immediate release formulation;and (ii) after the period of time in (i), administering to the patient asecond composition comprising a therapeutically effective amount of asecond active agent.

In some aspects, a method is provided for reducing one or moreside-effects associated with treatment with nitazoxanide or tizoxanidein a patient, the method comprising administering to the patient atherapeutically effective amount of a pharmaceutical composition in theform of a solid dosage form, the composition comprising (a) a firstportion comprising a first quantity of nitazoxanide or an analoguethereof in a controlled release formulation; and (b) a second portioncomprising a second quantity of nitazoxanide or an analogue thereof inan immediate release formulation.

In other aspects, a method is provided for increasing thebioavailability of nitazoxanide or an analogue thereof in a patient, themethod comprising administering to the patient a therapeuticallyeffective amount of a pharmaceutical composition in the form of a soliddosage form, the composition comprising (a) a first portion comprising afirst quantity of nitazoxanide or an analogue thereof in a controlledrelease formulation; and (b) a second portion comprising a secondquantity of nitazoxanide or an analogue thereof in an immediate releaseformulation.

In other aspects, a method is provided for extending absorption ofnitazoxanide or an analogue thereof in a patient, the method comprisingadministering to the patient a therapeutically effective amount of apharmaceutical composition in the form of a solid dosage form, thecomposition comprising (a) a first portion comprising a first quantityof nitazoxanide or an analogue thereof in a controlled releaseformulation; and (b) a second portion comprising a second quantity ofnitazoxanide or an analogue thereof in an immediate release formulation.

In yet other aspects, a controlled release tablet for oraladministration is provided, the tablet comprising nitazoxanide or ananalogue thereof and a low-viscosity polymer, wherein the low-viscositypolymer controls the release of the nitazoxanide or analogue thereof.

DETAILED DESCRIPTION

The present compositions are controlled release solid formulations ofnitazoxanide or nitazoxanide analogues, in particular, controlledrelease solid oral dosage forms comprising (a) a first portioncomprising a first quantity of nitazoxanide or an analogue thereof in acontrolled release formulation; and (b) a second portion comprising asecond quantity of nitazoxanide or an analogue thereof in an immediaterelease formulation. The formulations are typically in the form of abilayer tablet for oral administration. The compositions can be used toeffectively treat chronic hepatitis C and provide increasedbioavilability and better absorption of nitazoxanide, with fewer of theside effects commonly seen in standard nitazoxanide formulations.

Unless otherwise specified, “a” or “an” means “one or more.”

As used herein, the term “controlled release” refers to a property of apharmaceutical composition wherein the absorption and bioavailability ofthe active agent in the composition is maintained such thattherapeutically effective amounts of the active agent are bioavailableover an extended period of time.

As used herein, the term “immediate release” refers to a property of apharmaceutical composition wherein the active agent in the compositionis made bioavailable without substantial delay.

As used herein the terms “treating” and “treatment” refer to a reductionin severity and/or frequency of symptoms, elimination of symptoms and/orunderlying cause, prevention of the occurrence of symptoms and/or theirunderlying cause (e.g., prophylactic therapy), improvement orremediation of damage, or reduction in intensity of infection.

By the terms “effective amount” and “therapeutically effective amount”of a compound of the invention is meant a nontoxic but sufficient amountof the compound to provide the desired effect.

By “pharmaceutically acceptable” is meant a material that is notbiologically or otherwise undesirable, i.e., the material may beincorporated into a pharmaceutical composition administered to a patientwithout causing any undesirable biological effects or interacting in adeleterious manner with any of the other components of the compositionin which it is contained. When the term “pharmaceutically acceptable” isused to refer to a pharmaceutical carrier or excipient, it is impliedthat the carrier or excipient has met the required standards oftoxicological and manufacturing testing or that it is included on theInactive Ingredient Guide prepared by the U.S. and Drug administration.

By “patient” is meant any animal for which treatment is desirable.Patients may be mammals, and typically, as used herein, a patient is ahuman individual.

The present solid compositions can comprise two portions, eachcontaining a quantity of nitazoxanide of nitazoxanide analogue. Thus, insome embodiments, the compositions comprise a first portion thatcontains nitazoxanide or analogue in a controlled release formulation,and a second portion contains nitazoxanide analogue in an immediaterelease formulation. In some embodiments, the solid composition is inthe form of a tablet in which the immediate release portion is in theform of a layer that is deposited on top of the controlled releaseportion, and compressed to form a tablet. The solid dosage form can alsobe in the form of a capsule containing both controlled release granulesand immediate release granules.

The present formulations contain nitazoxanide or an analogue thereof asthe active agent. Methods of preparing nitazoxanide are known in thoseskilled in the art. See, e.g., U.S. Pat. No. 3,950,351 to Rossignol.Examples of nitazoxanide analogues and methods of preparing them aredisclosed in U.S. Pat. Nos. 7,285,567 and 6,117,894, and in publishedU.S. patent application nos. 2007/0167504, 2007/0015803, 2008/0097106,2008/0096941, and 2009/0036467. Each of these U.S. patents andpublications are incorporated by reference herein in their entireties.

As used herein, the term “nitazoxanide” refers to both nitazoxanide(2-(acetolyloxy)-N-(5-nitro-2-thiazolyl) benzamide) and to anitazoxanide analogue, e.g., to one of the compounds disclosed in U.S.Pat. No. 7,285,567 or US 2007/0167504.

Nitazoxanide or any of the nitazoxanide analogues may be administered inthe form of the compound per se, and/or, where suitable, in the form ofa salt, polymorph, ester, amide, prodrug, derivative, or the like,provided the salt, polymorph, ester, amide, prodrug or derivative issuitable pharmacologically. Such salts, esters, amides, prodrugs andother derivatives of these active agents may be prepared using standardprocedures known to those skilled in the art of synthetic organicchemistry and described, for example, by J. March, Advanced OrganicChemistry: Reactions, Mechanisms and Structure, 4th Ed. (New York:Wiley-Interscience, 1992). For any nitazoxanide analogue active agentsthat may exist in enantiomeric forms, the active agent may beincorporated into the present compositions either as the racemate or inenantiomerically enriched form.

The total amount of nitazoxanide in the present compositions istypically about 60% to 75% by weight of the composition. In thoseembodiments having controlled release and immediate release portions,the quantity of nitazoxanide in the controlled release portion istypically greater than the quantity in the immediate release portion,with the ratio of the quantity of nitazoxanide in the controlled releaseportion to the nitazoxanide in the immediate release portion being about2.5-4.0:1. For example, in some embodiments, the controlled releaseportion contains about 500 mg of nitazoxanide, and the immediate releaseportion contains about 175 mg of nitazoxanide. In other embodiments, thecontrolled release portion contains about 250 mg of nitazoxanide, andthe immediate release portion contains about 87.5 mg of nitazoxanide.

The compositions can contain one or more additional pharmaceuticallyacceptable additives or excipients. In those embodiments with controlledrelease and immediate release portions, both the controlled releaseportion and the immediate release portion can contain one or moreadditional pharmaceutically acceptable additives or excipients. Theseexcipients are therapeutically inert ingredients that are well known andappreciated in the art. As used herein, the term “inert ingredient”refers to those therapeutically inert ingredients that are well known inthe art of pharmaceutical science, which can be used singly or invarious combinations, and include, for example, diluents, disintegrants,binders, suspending agents, glidants, lubricants, fillers, coatingagents, solubilizing agent, sweetening agents, coloring agents,flavoring agents, and antioxidants. See, for example, Remington: TheScience and Practice of Pharmacy 1995, edited by E. W. Martin, MackPublishing Company, 19th edition, Easton, Pa.

Examples diluents or fillers include, but are not limited to, starch,lactose, xylitol, sorbitol, confectioner's sugar, compressible sugar,dextrates, dextrin, dextrose, fructose, lactitol, mannitol, sucrose,talc, microcrystalline cellulose, calcium carbonate, calcium phosphatedibasic or tribasic, dicalcium phosphaste dehydrate, calcium sulfate,and the like.

Diluent(s) or filler(s) typically represent about 10% to 15% by weightof the controlled release or immediate release portion, or about 2% toabout 15% by weight of the entire composition.

Examples of disintegrants include, but are not limited to, alginic acid,methacrylic acid DVB, cross-linked PVP, microcrystalline cellulose,sodium croscarmellose, crospovidone, polacrilin potassium, sodium starchglycolate, starch, including corn or maize starch, pregelatinized starchand the like.

Disintegrant(s) typically represent about 10% to 15% by weight of thecontrolled release or immediate release portion, or about 2% to about15% by weight of the entire composition.

Examples of binders include, but are not limited to, starches such aspotato starch, wheat starch, corn starch; microcrystalline cellulose;celluloses such as hydroxypropyl cellulose, hydroxyethyl cellulose,hydroxypropylmethyl cellulose (HPMC), ethyl cellulose, sodium carboxymethyl cellulose; natural gums like acacia, alginic acid, guar gum;liquid glucose, dextrin, povidone, syrup, polyethylene oxide, polyvinylpyrrolidone, poly-N-vinyl amide, polyethylene glycol, gelatin, polypropylene glycol, tragacanth, and the like.

Binder(s) typically represent about 2% to 15% by weight of thecontrolled release or immediate release portion, or about 0.2% to about14% by weight of the entire composition.

Examples of glidants include, but are not limited to, silicon dioxide,colloidal anhydrous silica, magnesium trisilicate, tribasic calciumphosphate, calcium silicate, magnesium silicate, colloidal silicondioxide, powdered cellulose, starch, talc, and the like.

Glidant(s) typically represent about 0.1% to 0.5% by weight of thecontrolled release or immediate release portion, or about 0.01% to about0.3% by weight of the entire composition.

Examples of lubricants include, but are not limited to, magnesiumstearate, aluminum stearate, calcium stearate, zinc stearate, stearicacid, polyethylene glycol, glyceryl behenate, mineral oil, sodiumstearyl fumarate, talc, hydrogenated vegetable oil and the like.

Lubricant(s) typically represent about 0.5% to 1.5% by weight of thecontrolled release or immediate release portion, or about 0.2% to about1.0% by weight of the entire composition.

For example, in some embodiments, the controlled release portion, theimmediate release portion, or both contain a starch as the diluent, suchas corn or maize starch; sodium croscarmellose and the disintegrant;hydroxypropylcellulose, microcrystalline cellulose, and/or hydroxypropylmethylcellulose and the binder(s); dicalcium phosphate dehydrate as thefiller; colloidal anhydrous silica as the glidant; and magnesiumstearate as the lubricant.

The present controlled release compositions also contains a binder thatis a low-viscosity polymer. Examples of low-viscosity polymers include,but are not limited to, low-viscosity hydroxypropyl methylcellulosepolymers such as those sold by Dow Chemical under the tradename“Methocel®” (e.g., Methocel E50LV®, Methocel K100LV®, and MethocelF50LV®) and low-viscosity hydroxyethylcellulose polymers. Thelow-viscosity polymer controls the release of the nitazoxanide oranalogue thereof in the formulation.

The low-viscosity polymer is typically present at about 10% to about20%, or about 10% to about 15%, or preferably about 12%, of the totalweight of the entire composition, or, in those embodiments havingcontrolled release and immediate release portions, the low-viscositypolymer in the controlled release portion is typically present at about15% to about 20%, preferably about 18%, of the weight of the controlledrelease portion.

The present compositions can further comprise a coating material. Thecoating material is typically present as an outer layer on the dosageform that completely covers the formulation. For example, in someembodiments, the dosage form is an oral tablet in which the controlledrelease portion forms a first layer of the tablet and the immediaterelease portion forms a second layer that is deposited on top of thefirst layer to form a core tablet. In such embodiments, e.g., thecoating material can be in the form of an outer coating layer that isdeposited on top of the core tablet.

The coating material typically is about 1% to about 5% by weight of thecomposition.

The coating material can comprise hydroxypropylmethylcellulose and/orpolyethylene glycol, and can comprise one or more excipients selectedfrom the group comprising coating agents, opacifiers, taste-maskingagents, fillers, polishing agents, coloring agents, antitacking agentsand the like. For example, the coating material can contain titaniumdioxide as an opacifying agent. Examples of film-coating substances andmethods for using such coating substances are well known to those ofskill in the art.

For example, the coating material used in the present compositions canbe OPADRY AMB 80W91416 or OPADRY FX 63F97546, as in the examples below.

Methods of making solid pharmaceutical formulations are known to thoseof skill in the art of pharmaceutical formulations and can be employedto prepare the present compositions. See, for example, Remington: TheScience and Practice of Pharmacy (1995), edited by E. W. Martin, MackPublishing Company, 19th edition, Easton, Pa.

The present compositions can be used to effectively treat chronichepatitis C and provide increased bioavilability and better absorptionof nitazoxanide, with fewer of the side effects commonly seen instandard nitazoxanide formulations.

The compositions may be administered for any length of time suitable foreffective for treatment of hepatitis C. Any appropriate dosage andregimen may be used for the compositions. Administration can typicallybe carried out over a period of about 3 days to about 104 weeks, but maybe carried out over a period longer than 104 weeks and may even becarried out indefinitely. For example, treatment of hepatitis C usingthe present formulations will typically involve administration of theformulations over a period of 12, 24, or 48 weeks. Appropriate regimenscan be determined by a physician.

One or more additional active agents may be included in the presentpharmaceutical compositions and methods of treatment. For example, insome embodiments, the compositions may include one or more additionaltherapeutic agents useful in treating hepatitis C such as ribavirin, andimmune-stimulating agents including, but not limited to, interferonssuch as interferon α-2b, a derivative of interferon α-2b such as apolyethylene glycol-conjugated form of interferon α-2b, interferon α-2a,or interferon alfacon-1.

The composition and the additional active agent (e.g., an interferon)may be administered simultaneously, or separately, at the same time, orin different compositions (including in separate compositions that varyin dosage form, release profiles, and the like).

For example, in some embodiments, a patient suffering from hepatitis Cis first pretreated with one of the nitazoxanide compositions describedherein. The duration of the pretreatment period may be between about 3days and about 6 months, for example, between about 1 week and about 12weeks, and, as a further example, between about 1 week and about 4weeks. The pretreatment period can be followed subsequently by atreatment period wherein the pretreated patient is treated with eitheran interferon alone or an interferon plus nitazoxanide and, optionally,one or more additional agents such as an antiviral agent, e.g.,ribavirin. Any of the interferons described herein may be used duringthe treatment period. The duration of the treatment period can be anyduration that is required to obtain the desired response, and willtypically be between about 1 day and about 12 months or longer. Forexample, the treatment period may comprise weekly injections of aninterferon, and may involve a single week of treatment, 2-4 weeks oftreatment, 4-12 weeks of treatment, or more (such as 6 months, 1 year, 2years, or indefinitely).

It is to be understood that the description above as well as theexamples that follow are intended to illustrate and not limit the scopeof the invention. Other aspects, advantages and modifications within thescope of the invention will be apparent to those skilled in the art towhich the invention pertains.

EXAMPLES Example 1 Factors Affecting Bioavailability of Nitazoxanide

A study was performed to investigate the impact of each of the followingfactors on bioavailablity of nitazoxanide: (1) absorption of tizoxanidevs. nitazoxanide, (2) modifying site of release in GI tract, (3) effectof different polymers, and (4) effect of granulation in alcohol vs.water.

Six different nitazoxanide and/or tizoxanide formulations wereadministered orally with food to four healthy adult male volunteers toinvestigate each factor. Each of the volunteers received each of the sixformulations in six different treatment periods, each treatment periodbeing separated by at least one week. The formulations were administeredorally with food. Blood samples were taken at eleven time points:immediately before the dose and at 1, 2, 3, 4, 5, 6, 7, 8, 10 and 12hours post-dose. The following formulations were administered:

(1) an immediate-release (“IR”) nitazoxanide/tizoxanide tabletcontaining 500 mg of 99% nitazoxanide/1% tizoxanide as activeingredient;

(2) an immediate-release tizoxanide tablet containing 500 mg oftizoxanide as active ingredient;

(3) an enteric-coated IR nitazoxanide/tizoxanide tablet coated withACRYL-EZE® 70 mg (10% weight gain);

(4) a nitazoxanide/tizoxanide tablet containing 500 mg of 99%nitazoxanide, 1% tizoxanide as active ingredient, granulated in alcoholwith hydroxypropyl-methylcellulose (Metolose 90 SH) 100.000 SR asbinding agent and dicalciumphosphate dihydrate as filler;

(5) a nitazoxanide/tizoxanide tablet containing 500 mg of 99%nitazoxanide, 1% tizoxanide as active ingredient, granulated in waterwith hydroxypropyl-methylcellulose (Metolose 90 SH) 100.000 SR asbinding agent and dicalciumphosphate dihydrate as filler; and

(6) a nitazoxanide/tizoxanide tablet containing 450 mg of 99%nitazoxanide, 1% tizoxanide as active ingredient, granulated in waterwith hydroxypropyl-methylcellulose (Methocel K100LV), 100 cP as bindingagent and dicalciumphosphate dihydrate as filler (two tablets wereadministered to the patients).

Serum pharmacokinetic (PK) parameters were calculated from blood samplestaken from the volunteers. Median values for AUC_(t) (μg·hr/mL), C_(max)(μg/mL), C_(min) (μg/mL), and T_(max) (hr) are presented in Table 1.

TABLE 1 Median serum pharmacokinetic parameter values for tizoxanidefollowing administration of six different pharmaceutical formulationscontaining nitazoxanide and/or tizoxanide to four healthy adult malevolunteers AUC_(t) C_(max) C_(min) T_(max) Formulation μg*hr/mL μg/mLμg/mL (hr) (1) IR tablet, 500 mg¹ 38.07 9.75 0.05 3 (2) Tizoxanide, 500mg² 9.12 1.81 0.00 4 (3) Enteric coated IR tablet, 500 26.97 6.50 0.00 8mg³ (4) High-viscosity polymer (dry 2.88 0.72 0.00 7 granulated), 500 mg⁴ (5) High-viscosity polymer 2 (wet 6.14 1.49 0.00 8 granulated), 500 mg⁵ (6) Low-viscosity polymer (900 34.77 7.03 0.21 7 mg, 2 × 450 mgtablets) ⁶ ¹Standard immediate release tablet containing approximately500 mg of active ingredient, which is 99% nitazoxanide/1% tizoxanide.²Same formulation as IR tablet, except that active ingredient is 100%tizoxanide. ³IR tablet coated with ACRYL-EZE ® 70 mg (10% weight gain).⁴ 500 mg of active ingredient (99% nitazoxanide, 1% tizoxanide)granulated in alcohol with hydroxypropyl-methylcellulose (HPMC), 100,000centipoise (“cP”) (Metolose 90 SH 100.000 SR) as binding agent anddicalciumphosphate dihydrate as filler ⁵ 500 mg of active ingredient(99% nitazoxanide, 1% tizoxanide) granulated in water with HPMC, 100,000cP (Metolose 90 SH 100.000 SR) as binding agent and dicalciumphosphatedihydrate as filler ⁶ 450 mg of active ingredient (99% nitazoxanide, 1%tizoxanide) granulated in water with HPMC, 100 cP (Methocel K100LV). Twotablets were administered to these patients.

Surprisingly, bioavailability was much lower following oraladministration of tizoxanide (Formulation 2) compared to nitazoxanide(Formulation 1).

The enteric coating of the IR nitazoxanide/tizoxanide tablet(Formulation 3) delayed absorption in two patients as evidenced by theincrease in T_(max) from 3 to 8 hours, but it also prevented absorptionin the other two patients.

The high-viscosity polymer (HPMC 100,000 cP) in Formulations 4 and 5essentially prevented absorption.

Granulation in water using the high-viscosity polymer (Formulation 5)improved absorption compared to granulation in alcohol (Formulation 4).

Reduction of viscosity of HPMC to 100 cP (Formulation 6) resulted in asignificant improvement in absorption (AUC_(t)), but absorption wasstill inferior to that of the IR tablet. Furthermore, even with delayedabsorption and use of a higher 900 mg dose, tizoxanide was eliminatedrapidly from serum so that the tizoxanide concentration in serum at 12hours post-dose was below 2 μg/mL in all 4 patients (median 1.28 μg/mL).

Example 2 Bilayer Tablet Formulation

A bilayer tablet containing a total of 650 mg of nitazoxanide was madeusing standard formulation techniques, as described above. Thecomposition of the bilayer tablet is presented in Table 2.

TABLE 2 Composition of Nitazoxanide 675 mg controlled release tablet.Unit formula Reference to INGREDIENTS (mg/tablet) Function Standards*Immediate Release Layer Nitazoxanide 175 Active Monograph substanceNon-active substances: Maize starch 36 Diluent/ Ph. Eur. 0344disintegrant Hydroxypropylcellulose 5 Binder/ Ph. Eur. 0337 (Klucel EF)suspending agent Sodium croscarmellose 7.5 Disintegrant Ph. Eur. 0985Colloidal anhydrous silica 1 Glidant Ph. Eur. 0434 (Aerosil 200)Microcrystalline cellulose 23 Dry binder Ph. Eur. 0316 Magnesiumstearate 2.5 Lubricant Ph. Eur. 0229 Water, Purified 50 Solvent Ph. Eur.0008 Controlled Release Layer Nitazoxanide 500 Active Monographsubstance Non-active substances: Hydroxypropyl-cellulose 2.5 Binder/ Ph.Eur. 0337 (Klucel EF) suspending agent Hydroxypropyl- 135 Binder/ Ph.Eur. 0348 methylcellulose suspending (Methocel E50LV) agentDicalciumphosphate 102.5 Filler Ph. Eur. 0116 dihydrate (Emcompress)Colloidal anhydrous silica 3 Glidant Ph. Eur. 0434 (Aerosil 200)Magnesium stearate 7 Lubricant Ph. Eur. 0229 Water, Purified 60 SolventPh. Eur. 0008 Coating Materials OPADRY AMB 40 Coating In house 80W91416,GREEN Monograph (contains c.i. pigment blue 63, polyvinyl alcohol, talc,lecithins, xanthan gum, titanium dioxide, c.i. pigment yellow 42) OPADRYFX 63F97546, 5 Coating In house Gloss (contains polyvinyl Monographalcohol, talc, polyethylene glycol, mica-based pearlescent pigment,polysorbate 80) Water, Purified 326 Solvent Ph. Eur. 0008 *Referencesare to current editions.

Example 3 Batch Formulation of Bilayer Tablets

A batch of 100,000 nitazoxanide bilayer tablets (650 mg) of Example 2was prepared as indicated in Table 3.

TABLE 3 Manufacturing batch formula for Nitazoxanide 675 mg controlledrelease tablets Unit formula Batch Formula INGREDIENTS (mg/tablet)(100,000 tablets) Immediate Release Layer Nitazoxanide 175 17.5 kgNon-active substances: Maize starch 36 3.6 kg Hydroxypropylcellulose(Klucel EF) 5 0.5 kg Sodium croscarmellose 7.5 0.75 kg Colloidalanhydrous silica (Aerosil 200) 1 0.1 kg Microcrystalline cellulose 232.3 kg Magnesium stearate 2.5 0.25 kg Water, Purified 50 5 kg ControlledRelease Layer Nitazoxanide 500 50 kg Non-active substances:Hydroxypropyl-cellulose (Klucel EF) 2.5 0.25 kgHydroxypropyl-methylcellulose 135 13.5 kg (Methocel E50LV)Dicalciumphosphate dihydrate 102.5 10.25 kg (Emcompress) Colloidalanhydrous silica (Aerosil 200) 3 0.3 kg Magnesium stearate 7 0.7 kgWater, Purified 60 6 kg Coating Materials: OPADRY AMB 80W91416, GREEN 404 kg contains c.i. pigment blue 63, polyvinyl alcohol, talc, lecithins,xanthan gum, titanium dioxide, c.i. pigment yellow 42 OPADRY FX63F97546, Gloss 5 0.5 kg (contains polyvinyl alcohol, talc, polyethyleneglycol, mica-based pearlescent pigment, polysorbate 80) Water, Purified326 32.6 kg

The tablets were produced following the manufacturing protocol outlinedbelow.

A. Equipment

-   -   Frewitt sieve    -   Collette Planetary blender    -   Drying oven    -   Tabletting machine—Manesty BB press    -   Tablet deduster    -   Coating apparatus—Accelacota

All production equipment is cleaned prior to use.

B. Preparation of Immediate Release Granulate (Granulate A)

-   -   1. The raw materials are weighed into sealed plastic bags.    -   2. The integrity of the machine is checked before and after use.    -   3. If necessary, the nitazoxanide and maize starch are sieved        through a 1.25 mm mesh sieve using a Frewitt machine.    -   4. These ingredients are transferred to the bowl of a Collette        Planetary Blender and blended for 15 minutes at low speed.    -   5. Dissolve hydroxypropylcellulose (HPC) in water, allow to        stand overnight.    -   6. This HPC solution is slowly added with mixing and the content        is mixed for 5-10 minutes at low speed.    -   7. If necessary, add extra water.    -   8. The granulate is sieved through a 4 mm mesh sieve using a        Frewitt machine, put on trays and dried at 50° C. for 12 to 16        hours.    -   9. The trays are removed from the oven, samples are taken to        test for loss on drying.    -   10. The dried granulate is re-sieved through a 1.25 mm mesh        sieve using a Frewitt machine and transferred to the drum of the        blender.    -   11. The aerosil, sodium croscarmellose and microcrystalline        cellulose are sieved through a 1.25 mm mesh sieve using a        Frewitt machine and added to the above and mixed for 15 minutes        at low speed.    -   12. Magnesium stearate is sieved through a 1.25 mm mesh sieve        using a Frewitt machine and added to the above and mixed for 4        minutes at low speed.

C. Preparation of Controlled Release Granulate (Granulate B)

-   -   1. The raw materials are weighed into sealed plastic bags.    -   2. The integrity of the machine is checked before and after use.    -   3. Nitazoxanide is transferred to the bowl of a Collette        Planetary Blender.    -   4. Dissolve HPC in water, allow to stand overnight.    -   5. The HPC solution is slowly added with mixing and the content        is mixed for 5-10 minutes at low speed.    -   6. If necessary, add extra water.    -   7. The granulate is sieved through a 4 mm mesh sieve using a        Frewitt machine, put on trays and dried at 50° C. for 12 to 16        hours.    -   8. The trays are removed from the oven, samples are taken to        test for loss on drying.    -   9. The dried granulate is re-sieved through a 1.25 mm mesh sieve        using a Frewitt machine and transferred to the drum of the        blender.    -   10. Hydroxypropylmethylcellulose, dicalciumphosphate dihydrate        and aerosil are sieved through a 1.25 mm mesh sieve using a        Frewitt machine.    -   11. These ingredients are added to the bowl of the Colette        Planetary Blender and blended for 15 minutes at low speed.    -   12. Magnesium stearate is sieved through a 1.25 mm mesh sieve        using a Frewitt machine and added to the above and mixed for 4        minutes at low speed.

D. Tabletting

-   -   1. The tabletting is carried out using a Manesty BB press        tabletting machine (19 mm oblong biconvex punch).    -   2. Filling and precompression of granulate B: target weight=750        mg second filling with granulate A: target weight=250 mg and        final compression: final weight=1000 mg

The pressure is adjusted after visual inspection.

-   -   1. The tablets are dedusted.    -   2. Tablets are taken for weight control, friability, assay,        thickness and hardness.    -   3. The gross and net weight of tablets produced is recorded. If        these are not within ±5% of limits, reasons for losses must be        recorded.

E. Coating

-   -   1. Verify the identity of the material used for manufacturing        and the line clearance.    -   2. The tablets are transferred to the coating apparatus        (Accelacota).    -   3. Prepare the coating suspension as follows:        -   Transfer purified water into a suitable container.        -   Disperse the OPADRY AMB 80W91416, GREEN by means of rapid            stirring.        -   After all the OPADRY has been added, continue stirring for a            further 45 minutes.    -   4. Pour the coating suspension into the coating apparatus        (Accelacota).    -   5. Mix gently while the coating suspension is being sprayed.    -   6. Repeat step 32-34 with OPADRY FX 63F97546, Gloss.    -   7. Afterwards, verify the weight increase of 100 tablets. The        increase must be at least 35 mg/tablet.    -   8. Sampling and control of unit weight and disintegration.    -   9. After approval by Quality Assurance, transfer the tablets        into clean containers, lined with two polyethylene bags.

Example 4 Testing of Final Bilayer Tablets

The 675 mg nitazoxanide bilayer tablet described in Examples 2 and 3(“NTZ 675 mg tablet”) was tested in the following two clinical studies.

1. Study 16106-1001 (Pharmacokinetics and Tolerability Study in HealthyVolunteers Using 675 mg Controlled Release Tablets).

12 healthy adult volunteers were randomized in double-blind fashion toreceive one NTZ 675 mg tablet and one placebo tablet b.i.d. or two NTZ675 mg tablets b.i.d. for 7 days. After a 7-day washout period, eachsubject crossed over to receive 7 days of treatment with the dose thathe had not received during the first 7-day treatment period. Plasmasamples were collected for assay of NTZ metabolites, tizoxanide (T) andtizoxanide glucuronide (TG), over 12 hours following the first dose onday 1, before the morning dose on day 5 and day 6 and over 24 hoursfollowing the morning dose on day 7 (the last dose).

The following table presents important pharmacokinetic parameters fortizoxanide obtained after 7 days administration of the controlledrelease tablets compared to results obtained from a similar study usingthe nitazoxanide 500 mg immediate release (“IR”) tablet (Study 198.637).The total exposure (AUC) and minimum plasma concentrations (C_(min))were significantly higher for the controlled release tablet than for theIR tablet, but the maximum plasma concentrations were similar.

TABLE 4 Comparison of Important Pharmacokinetics Parameters forTizoxanide from Study RM06-1001 to Historical Data from a Similar Studyof the Nitazoxanide 500 mg Immediate Release Tablets CR Tablet IR Tablet675 mg 1350 mg 500 mg 1000 mg b.i.d. b.i.d. b.i.d. b.i.d. (n = 12) (n =11) (n = 6) (n = 5) AUC_(∞)(μg · h/mL) 78.3 221 52.3 158 C_(min) (μg/mL)1.26 5.39 0.40 2.14 C_(max) (μg/mL) 11.9 29.8 9.3 24.4

The values presented in Table 4 are arithmetic means. Data for CR tabletwere taken from study RM06-1001. Data for IR tablet was taken from study198.637. In both studies, the tablets were administered b.i.d. with foodfor 7 days in healthy adult male volunteers. The pharmacokineticparameters presented are for day 7 of b.i.d. dosing.

Only mild to moderate adverse events were observed in Study RM06-1001,the most common being chromaturia, fatigue, diarrhea, conjunctivaldiscoloration, abdominal pain and nausea. Adverse events occurring withgreater frequency during the high dose treatment were: diarrhea (8 [73%]versus 4 [33%] subjects), nausea (7 [64%] versus 3 [25%] subjects),abdominal pain (6 [55%] versus 2 [17%] subjects), and decreased appetite(4 [36%] versus 1 [8%] subjects). The occurrence rates of all otheradverse events were similar for the two treatment regimens. There wereno significant changes in clinical laboratory values, vital signs or ECGparameters.

Historically, the most common adverse events associated with oraladministration of nitazoxanide have been related to the gastrointestinaltract. The following table presents the most common gastrointestinaladverse events reported from Study RM06-1001 alongside those reported inStudy 198.637 using the 500 mg immediate release (IR) tablet. The datain Table 5 indicate that the controlled release tablet is bettertolerated than the immediate release tablet.

TABLE 5 Comparison of Numbers of Patients Reporting Most CommonGastrointestinal Adverse Events from Phase I Clinical Studies in HealthyMale Volunteers: Studies RM06-1001 and 198.637 Placebo CR Tablet IRTablet CR Tablet IR Tablet IR Tablet 675 mg 500 mg 1350 mg 1000 mg BIDBID BID BID BID (n = 4) ¹ (n = 12) ² (n = 6) ¹ (n = 11) ² (n = 6) ¹Abdominal 1, 25% 2, 17% 3, 50% 6, 55% 6, 100%  pain Diarrhea 2, 50% 4,33% 4, 67% 8, 73% 5, 83% Flatulence 2, 50%  0, 0% 1, 17%  0, 0% 4, 67%Nausea  0, 0% 3, 25%  0, 0% 7, 64% 4, 67% Total 5   9   8   21    21  Total/n 1.25 0.75 1.25 1.91 3.5 Moderate  0, 0%  0, 0%  0, 0% 4, 37% 3,50% AEs³ Discontin-  0, 0%  0, 0%  0, 0%  0, 0% 1, 17% uations⁴ ¹ Fromstudy 198.637. ² From study RM06-1001. ³All other adverse events weremild. ⁴Discontinuations due to adverse events.

Data for the CR tablet was taken from study RM06-1001 (final report inpreparation). Data for the IR tablet and the placebo tablets were takenfrom study 198.637. In both studies, the tablets were administeredb.i.d. with food for 7 days in healthy adult male volunteers. Bothstudies were conducted at the same clinical center by SGS Biopharma(CRO), and both studies were double-blinded so that neither the patientsor physicians were aware of treatment group assignment. The study of theIR tablet was conducted in 1998, and the study of the CR tablet wasconducted in 2008.

2. Study RA406-1002 (Viral Kinetics Study in Patients with ChronicHepatitis C Genotype 4 Using 675 mg Controlled Release Tablets).

40 interferon-naive patients with chronic hepatitis C genotype 4 wererandomized (2:2:1) in double-blind fashion to receive NTZ 675 mg b.i.d.for 4 weeks followed by NTZ 675 mg b.i.d.+PegIFN+RBV for 48 weeks, NTZ1350 mg b.i.d. for 4 weeks followed by NTZ 1350 mg b.i.d.+PegIFN+RBV for48 weeks, or placebo b.i.d. for 4 weeks followed by placebo+PegIFN+RBVfor 48 weeks. Dosing of PegIFN (peginterferon alfa-2a, Pegasys®, Roche,Basel, Switzerland) was 180 μg/week, and dosing of RBV (Viracure®,October Pharma, Cairo, Egypt) was 1000 mg/day (weight <75 kgs), or 1200mg/day (body weight≥75 kgs). HCV RNA was quantified at baseline and ondays 3, 7, 14 and 28 during the monotherapy lead-in phase and on days 3,7, 14 and 28 of the combination therapy phase. The primary endpoint wasthe change in quantitative HCV RNA from baseline to week 4 ofcombination therapy. Secondary endpoints included RVR (HCV RNA<12 IU/mLafter 4 weeks of combination therapy), cEVR (HCV RNA<12 IU/mL after 12weeks of combination therapy) and EVR (≥2 log₁₀ drop in HCV RNA after 12weeks of combination therapy). HCV RNA was quantified using the AbbottRealtime HCV RT-PCR assay (LOD=12 IU/mL)

Virologic response through study week 16 is described in the tablebelow.

TABLE 6 Virologic Response to Treatment Using Controlled Release Tablets1350 mg BID + 675 mg BID + Placebo + PEG + RBV PEG + RBV PEG + RBV (n =16) (n = 17) (n = 8) Mean reduction of HCV −4.4 −3.9 −3.5 RNA frombaseline to week 4 of combination therapy (log10 IU/mL) RVR 10 (63%)  10(59%) 4 (50%) cEVR 16 (100%) 14 (82%) 5 (63%) EVR 16 (100%) 15 (88%) 5(63%)

No serious adverse events were reported, and no patients discontinuedtreatment due to an adverse event.

This study demonstrated a dose-related improvement in virologic responseto therapy. In a previous study in patients with chronic hepatitis Cgenotype 4 who were treated with the IR tablet twice daily pluspeginterferon alfa-2a and ribavirin, the proportion of patientsachieving undetectable levels of HCV RNA after 12 weeks of combinationtherapy (cEVR) was 86% (24/28). Use of the new controlled release tabletformulation with fewer side effects allowed us to increase the dose ofactive ingredient to 1350 mg twice daily, improving the concentrationsof tizoxanide in plasma and improving the proportion of patientsachieving cEVR.

Although the foregoing refers to particular preferred embodiments, itwill be understood that the present invention is not so limited. It willoccur to those of ordinary skill in the art that various modificationsmay be made to the disclosed embodiments and that such modifications areintended to be within the scope of the present invention.

All of the publications, patent applications and patents cited in thisspecification are incorporated herein by reference in their entirety.

What is claimed is:
 1. A pharmaceutical composition in the form of asolid oral dosage form comprising: (a) a first portion comprising afirst quantity of nitazoxanide or an analogue thereof in a controlledrelease formulation; and (b) a second portion comprising a secondquantity of nitazoxanide or an analogue thereof in an immediate releaseformulation.
 2. The composition of claim 1, wherein the solid oraldosage form is a tablet.
 3. The composition of claim 2, wherein thefirst portion (a) forms a first layer of the tablet, and the secondportion (b) forms a second layer deposited on top of the first layer(a).
 4. The composition of claim 2, wherein the first portion (a) formsa first layer of the tablet; the second portion (b) forms a second layerthat is deposited on top of the first layer (a) to form a core tabletcomprising the first layer and the second layer; and (c) an outercoating layer that is deposited on top of the core tablet.
 5. Thecomposition of claim 1, wherein the solid oral dosage form is a capsule.6. The composition of claim 5, wherein the first portion (a) is in theform of controlled-release granules containing the first quantity ofnitazoxanide or analogue thereof, and the second portion (b) is in theform of immediate-release granules containing the second quantity ofnitazoxanide or analogue thereof.
 7. The composition of claim 1, whereinthe first portion further comprises one or more diluents, disintegrants,binders, suspending agents, glidants, lubricants, fillers, or additionalexcipients.
 8. The composition of claim 7, wherein the first portionfurther comprises hydroxypropylcellulose andhydroxypropylmethylcellulose as the binders, dicalciumphosphatedehydrate as the filler, colloidal anhydrous silica as the glidant, andmagnesium stearate as the lubricant.
 9. The composition of claim 1,wherein the second portion further comprises one or more diluents,disintegrants, binders, suspending agents, glidants, lubricants,fillers, or additional excipients.
 10. The composition of claim 9,wherein the second portion further comprises hydroxypropylcellulose andmicrocrystalline cellulose as the binders, maize starch as the diluent,sodium croscarmellose as the disintegrant, colloidal anhydrous silica asthe glidant, and magnesium stearate as the lubricant.
 11. Thecomposition of claim 1, wherein the first portion further comprises alow viscosity polymer.
 12. The composition of claim 11, wherein the lowviscosity polymer is a low viscosity hydroxypropyl-methylcellulose. 13.A controlled release tablet for oral administration, the tabletcomprising nitazoxanide or an analogue thereof and a low-viscositypolymer, wherein the low-viscosity polymer controls the release of thenitazoxanide or analogue thereof.
 14. The controlled release tablet ofclaim 13, wherein the low-viscosity polymer is a low-viscosityhydroxypropylmethylcellulose.